JPH02139559A - Preparation of resist pattern to be used in semiconductor device - Google Patents

Abstract

PURPOSE:To improve sensitivity and heat resistance of a resist compsn. to be used in a semiconductor device and to permit extremely fine working by using a specified photosensitive compsn. CONSTITUTION:A photoresist layer consisting of an alkali-soluble resin(e.g. cresol novolak resin) blended with >=3wt.% compd. expressed by the formula is formed on a semiconductor wafer. The photoresist layer is then exposed to active rays(e.g. ultraviolet rays) through a specified mask, and the exposed part is dissolved selectively with weak alkaline aq. soln. and removed to form a resist pattern. In the formula, D is a naphthoquinone-1,2-diazide-5-sulfonyl group or a naphthoquinone-1,2-diazide-4-sulfonyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a heat-resistant resist pattern for semiconductor devices such as ICs and LSIs that require ultrafine processing.

Conventionally, in the manufacturing process of semiconductor devices such as ICs and LSIs, a thin film of a photoresist composition is formed on a silicon wafer as microfabrication using a photoetching method, and a mask pattern with a semiconductor device pattern is formed on the thin film of a photoresist composition on a silicon wafer. A method is used in which the resist pattern is transferred by irradiation with ultraviolet rays or the like and then developed, and the silicon wafer is etched using the resist pattern thus obtained as a protective film. In this method, in order to obtain a thin film of a photoresist composition having a uniform thickness, the photoresist composition is usually dissolved in an organic solvent, and this solution is applied using a spinner or the like. The organic solvent used at this time is
Ketones, esters, and cellosolves that have good dissolution ability for the composition are considered optimal, and are limited to those with a boiling point in the range of 125 to 165°C from the viewpoint of uniformity of application and drying properties. There is.

By the way, as a positive photoresist composition, naphthoquinone-1,2-diazide sulfonic acid ester (hereinafter abbreviated as azido ester) of an aromatic polyhydroxy compound is used.
It is already known that those containing as a photosensitive component are suitable. However, when a photoresist composition containing this azide ester is dissolved in an organic solvent to form a solution of the photoresist composition, although the azide ester dissolves extremely well in a ketone solvent, it decomposes significantly in the solution. Storage stability is a problem, and in ester-based solvents and cellosolve-based solvents, although the storage stability of the azide ester is good, the solubility is not good, and fine crystals may precipitate over time. many. For this purpose, aromatic polyhydroxy compounds in azide esters, phenolic novolac resins,
The aromatic polyhydroxy compounds used in azide esters for higher sensitivity are limited to Fres/-Fle/borac resins, gallic acid esters, polyhydroxybenzophenones, etc. Among these, aromatic polyhydroxy compounds that contain a particularly large number of hydroxyl groups per unit molecule are used. It is usually selected from gallic acid esters and polyhydroxybenzophenones. Naphthoquinone-1 of polyhydroxybenzophenones
, 2-diazide sulfonic acid esters, for example, the use of diesters and triesters of tetrahydroxybenzophenones for the production of printing plates has been proposed (U.S. Pat. No. 3,106,465; 3.148°983 Specification).

In these polyhydroxybenzophenones, 7-toquinone-1,2-diazide sulfonic acid esters,
The presence of a hydrogen bond between the carbonyl group of the benzophenone nucleus and the hydroxyl group ensures solubility in organic solvents and compatibility with the resin used in combination, so at least one hydroxyl group remains in a free form. That is what is needed.

Problems to be Solved by the Invention However, these known naphthoquinone-1,2-diazide sulfonic acid esters of polyhydroxybenzophenones do not pose any particular problems in applications that do not require much precision, such as printing plates. In applications requiring ultrafine processing such as semiconductor devices, the sensitivity is insufficient and the heat resistance is not necessarily satisfactory. Therefore, the reality is that no satisfactory method for obtaining semiconductor devices has been known to date.
child.

An object of the present invention is to provide a method for manufacturing a resist pattern for manufacturing a semiconductor device such as an IC1LSI that requires ultrafine processing.

Means for Solving the Problems As a result of extensive research, the present inventors used naphthoquinone-1,2-diazidosulfonic acid tetraester of 2.3.4.4'-tetrahydroxybenzophenone as a photosensitive component. As a result, the inventors discovered that the above object could be achieved, and based on this knowledge, they completed the present invention.

Until now, for naphthoquinone-1,2-diazide sulfonic acid ester of tetrahydroxybenzophenone, although it has been thought that the presence of at least one free hydroxyl group is necessary, as mentioned above, all hydroxyl groups are It was completely unexpected that substituted tetraesters are suitable for ultrafine processing and exhibit excellent heat resistance.

That is, the present invention provides - maximum (in the formula D is 7-toquinone-1,2-diazide-5-sulfonyl group or 7-toquinone-1,2-diazide-4.
After coating a semiconductor wafer with an alkali-soluble resin containing a photosensitive component containing at least 3% by weight of a compound represented by a sulfonyl group to form a photoresist layer, actinic radiation is applied to the photoresist layer through a prescribed mask pattern. The present invention provides a method for producing a resist pattern for a semiconductor device, which comprises irradiating the resist pattern and then selectively dissolving and removing the exposed portion with a weakly alkaline aqueous solution.

In the method of the present invention, the compound represented by the above-mentioned maximum (1) contained in the photosensitive component of the photoresist layer is 2.
3.4.4'-Tetrahydroxybenzophenone 7
toquinone-1,2-diazido-5-sulfonic acid tetraester or naphthoquinone-1,2-diazide-4-sulfonic acid tetraester, which are, for example, 2.3
, 4,4'-Tetrahydroxybenzophenone and naphthoquinone-1,2-diazide-5-sulfonyl chloride or 7-toquinone-1,2-diazide-4-sulfonyl chloride are dissolved in dioxane, and the solution is dissolved in alkali carbonate or hydrogen carbonate at room temperature. It can be produced by dropping an aqueous alkali solution to cause a condensation reaction, then neutralizing and purifying the reaction product.

The content of the compound represented by maximum (1) in the composition of the present invention must be 3% by weight in the photosensitive component, and if the amount is less than this, the effect will not be fully exhibited.

In addition to the compound represented by (I) above, this photosensitive component may optionally contain 2,3,4,4'-tetrahydroxybenzophenone, Not only esters, diesters, and monoesters, but also other quinonediazide group-containing compounds, such as orthobenzoquinonediazide, parabenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide, or their nuclear substituted derivatives such as orthonaphthoquinonediazide sulfonic acid esters; Furthermore, compounds having orthoquinonediazide sulfonyl chloride and a hydroxyl group or an amino group, such as phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A1 naphthol, pyrocatechol, pyrogallol, pyroga, roll monomethyl ether, pyrogallol-1,3-dimethyl ether , gallic acid, esterified or etherified I with some hydroxyl groups left; reaction products with gallic acid, aniline, p-aminodiphenylamine, etc. can be used in combination as long as they are compatible.

In the method of the present invention, an alkali-soluble resin is used as a coating material for the photoresist layer.

Examples of the alkali-soluble resin include novolac resins produced from aldehydes such as phenol or cresol, polyvinyl alcohol, polyvinyl alkyl ethers, copolymers of styrene and acrylic acid, and methacrylic acid and methacrylic acid alkyl esters. Examples include copolymers, hydroxystyrene polymers, polyvinylhydroxybenzoate, and polyvinylhydroxybenzal.

These alkali-soluble resins are usually used in an amount of 5 parts by weight per 10 parts by weight of the photosensitive component containing the compound represented by maximum (I) above.
It is used in a range of 200 parts by weight, preferably 10 to 60 parts by weight. If the amount of alkali-soluble resin is too large, the fidelity of the resist image will be poor and the transferability will be poor, and if it is too small, the uniformity of the resist film will be poor and the resolution will also be reduced.

For forming the photoresist layer in the method of the present invention, it is preferable to use the photosensitive component and the alkali-soluble resin dissolved in a suitable solvent in the form of a solution.

Examples of such solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, isoamyl ketone; monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether of ethylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol heptanoacetate; Alternatively, polyhydric alcohols such as monophenyl ether, derivatives thereof, cyclic ethers such as dioxane, and esters such as methyl acetate, ethyl acetate, and butyl acetate can be mentioned. These may be used alone or in combination of two or more.

Among these, polyhydric alcohols and their derivatives, so-called cellosolve solvents, are particularly preferably used in photoresist compositions for microfabrication of semiconductor devices.

This photoresist layer may further contain compatible additives, such as sensitizers to increase the sensitivity of the photosensitive component, additional resins to improve resist film performance, plasticizers, stabilizers, etc., as required. It is possible to add and contain commonly used agents such as agents or coloring agents to make the developed image more visible.

To illustrate one embodiment of the method of the present invention, first, a solution of a photosensitive component and an alkali-soluble resin such as a phenol novolac resin dissolved in an appropriate solvent as described above is placed on a support such as a silicon wafer using a spinner. Apply with
A light source that dries to form a photosensitive layer and then emits ultraviolet light, such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp,
Exposure is performed through a required mask pattern using an arc lamp, xenon lamp, etc., or irradiation is performed while scanning an electron beam. Next, when this is immersed in a developing solution, for example, a weakly alkaline aqueous solution such as a 1-2% aqueous sodium hydroxide solution, the portions made solubilized by exposure are selectively dissolved and removed, resulting in an image faithful to the mask pattern. Can be done.

Effects of the Invention In the method of the present invention, at least 3% by weight of naphthoquinone-1,2-diazide-5-sulfonic acid tetraester of 2.3.4.4'-tetrahydroxybenzophenone or naphthoquinone-1, 2-Diazide-
One containing 4-sulfonic acid tetraester is used,
This product has extremely good compatibility with solvents, so when it is used as a solution, precipitation of fine crystals over time is not observed. Further, the photosensitive component is a conventionally known 2.3
．． 4-Trihydroxybenzophenone 7-toquinone-1.2-; Superior sensitivity and heat resistance compared to acidosulfonic acid triester, for example, when the same alkali-soluble resin is used and the blending ratio of the resin and photosensitive component is the same When the photoresist layer in the method of the present invention is 2.3
．． It has about 1.5 times the sensitivity of a composition using naphthoquinone-1,2-diazide sulfonic acid triester of 4-trihydroxybenzophenone, and is also superior in heat resistance by about 30°C.

As described above, since the method of the present invention uses a photoresist layer with excellent sensitivity and heat resistance, the time required to form an image by irradiating ultraviolet rays is shorter than when using conventionally known photoresists. This improves work efficiency. Furthermore, the resist pattern obtained by the method of the present invention has excellent dry etching properties and is particularly suitable for use in manufacturing semiconductor devices such as ICs and LSIs.

Example Next, the present invention will be explained in more detail with reference to Examples.

Reference example 1 2.3.4.4'-tetrahydroxybenzophenone 9
．． 89 (0,04 mol) and naphthoquinone-1,2-diazide-5-sulfonyl chloride 26.89 (0,1
0 mol) was dissolved in 340 g of dioxane, and 24 g of a 25% by weight aqueous sodium carbonate solution was added dropwise thereto over 30 minutes to 1 hour while stirring thoroughly. Next, a diluted hydrochloric acid solution prepared by diluting 35% by weight hydrochloric acid 259 with ion-exchanged water 10009 was added to precipitate the reaction product, and the resulting precipitate was thoroughly washed with ion-exchanged water, water was removed, and then dried.

The dried product thus obtained was dissolved in tetrahydrofuran, and a Hitachi 655 liquid chromatograph (manufactured by Hitachi Seisakusho, three columns 5hodex KF-801 (manufactured by Showa Kosha) and a GPC column)), UVIDEO -10
Using a 0■ type ultraviolet detector (manufactured by JASCO Corporation), wavelength 31
As a result of analysis at 0 nm, the composition according to the sensitivity at a wavelength of 310 nm was 26.4% tetraester in terms of area ratio.
, diester 37.1%, monoester 24.2%, unreacted material! It was 2.3%.

In addition, gel permeation chromatography (GP)
In C), only four reaction product peaks were detected, and based on their retention times, it was assumed that they were tetraesters, diesters, monoesters, and unreacted products. Its existence was not confirmed as it overlapped with the suso of

Reference Example 2 After the reaction product 109 of Reference Example 1 was completely dissolved in acetone 509, it was allowed to stand to precipitate. The precipitate was dried and the acetone was evaporated from the filtrate to obtain a sticky paste-like substance. According to the results of GPC analysis of the dry material and the paste-like material, the dry material is a tetraester with a purity of 99% or more, and the paste-like material is a tetraester with a purity of 3.
%, the remainder was a mixture consisting of diester, monoester and unreacted materials.

Reference example 3 2.3.4-trihydroxybenzophenone 9.2g
(0.04 mol) was used, but the reaction was carried out under the same charging ratio and reaction conditions as in Reference Example 1. As a result of GPC analysis of the obtained reaction product, 53.6% of triester, 29.7% of diester, Monoester 11.3%, unreacted matter 5
．． It was 4%.

Reference Example 4 After completely dissolving the reaction product log of Reference Example 3 in acetone 509, the precipitate that was left to stand was removed and the liquid was treated in the same manner as Reference Example 2 to obtain a dry powder and a paste-like substance. As a result of GPC analysis, the dry powder was a triester with a purity of 99% or more, and the paste-like material had a triester content of 10% or less.

Examples 1 to 3, Comparative Example L 2 Talesol novolak resin (molecular weight 30,000, polystyrene equivalent) 89, the reaction product of Reference Example 1, the dried product and paste substance of Reference Example 2, and the reference example as photosensitive components 2 g each of the dry substance and pasty substance of No. 4 were added to 23.3 g of ethylene glycol monoethyl ether acetate.
These were each applied to a silicon wafer using a spinner and dried on a hot plate at 110°C for 90 seconds to obtain a film thickness of 1.3 μm.
A resist film was obtained. This film was coated with an ultra-high pressure mercury lamp exposure device (
Using Canon PLA-500), from 1 second to 5
After exposure to light at intervals of 0.2 seconds, the sensitivity was determined by developing with a 2.38% by weight tetramethylammonium hydroxide aqueous solution for 1 minute, washing with water for 30 seconds, and drying. (minimum time required).

In this way, a resist pattern for a silicon wafer was obtained. Next, heat each resist pattern to 130℃.
, 140°, 0.150°C, 160°C, and 170°C for 20 minutes, and the heat resistance was evaluated as to whether the pattern was deformed or not. The following table shows the measurement results of sensitivity and heat resistance.

As can be seen, the tetraester of 2.3.4.4'-tetrahydroxybenzophenone is superior to the triester of 2.3.4-trihydroxybenzophenone in both sensitivity and heat resistance.

Example 4.5, Comparative Examples 3 to 5 Example 4.5 and Comparative Example 4.5 are respectively Example 2.3.
When preparing the photoresist compositions in Comparative Examples 1 and 2, the blending ratio of Talesol novolac resin and photosensitive component was
In order to keep the amount of sulfonyl groups constant, a self-recording spectrophotometer was used to compare the absorbance of cresol novolak resin (absorbance Abs 280 at a photosensitive wavelength of 280 nm) and naphthoquinone-
Example 2.3 and Comparative Example except that the ratio to the absorbance of the 1,2-diazide-5-sulfonyl group (absorbance Abs345 at a sensitivity wavelength of 345 nm) was constant, that is, Abs280/Abs345 = 3.90. It was prepared using the same method and conditions as 1.2, and its sensitivity and heat resistance were measured.

In Comparative Example 3, a photoresist composition was prepared in the same manner as described above except that the reaction product of Reference Example 3 was used as a photosensitive component, and the sensitivity and heat resistance were measured. These results are shown in the table below.

As can be seen, the tetraester of 2.3.4.4'-tetrahydroxybenzophenone is
-It has better sensitivity and heat resistance than triester of trihydroxybenzophenone.

Comparative Example 6 The reaction was carried out under the same conditions as in Reference Example 1 except that 9.8 g of 2.2',4.4'-tetrahydroxybenzophenone was used, and the resulting reaction product was analyzed by GPC. 73.4% and 2361 respectively
% of the reactant was 3.5%. 2 g of this reaction product and cresol novolak resin (molecular weight 30,000, polystyrene equivalent) 89 were dissolved in 23.3 g of ethylene glycol monoethyl ether acetate.
The compatibility of each photoresist composition obtained in Example No. 5 to No. 5 was compared.

As a result, in Examples 1 to 5 and Comparative Examples 1 to 5,
Although no precipitate was observed in the photoresist composition even after one week had elapsed, in this example, precipitate was precipitated.

Claims (1)

[Claims] 1 General formula▲ Numerical formula, chemical formula, table, etc.▼ (D in the formula is naphthoquinone-1,2-diazide-5-sulfonyl group or naphthoquinone-1,2-diazide-4-
After coating a semiconductor wafer with an alkali-soluble resin containing a photosensitive component containing at least 3% by weight of a compound represented by a sulfonyl group to form a photoresist layer, actinic radiation is applied to the photoresist layer through a prescribed mask pattern. 1. A method for producing a resist pattern for a semiconductor device, comprising irradiating the resist pattern and then selectively dissolving and removing the exposed portion with a weakly alkaline aqueous solution.